P. Doll

The quasihole aspect of hole strength distributions in odd potassium and calcium isotopes

Abstract The 40,42,44,48 Ca ( d , ρ) 39,41,43,47 K and 40,44 Ca(d, t) 39,43 reactions have been studied at 52 MeV. Angular distributions have been taken and spectroscopic factors have been extracted by means of a DWBA analysis for states with excitation energies up to typically 10 MeV. Analog relations are proposed for mass-39 and mass-43 nuclei. A discussion of proton occupation numbers for various shells above and below the Fermi surface shows a substantial and about equal core excitation for 42Ca and 44Ca. Typically 70 % of the 1 d 5 2 hole strengths have been located. The corresponding energy averaged strength distributions show quasihole structures whose widths are dominated by phonon-hole coupling to the first 2+ state in the target nucleus.

Spins of proton hole states from analyzing powers of (d, τ) reactions at 52 MeV

Large and characteristic vector-analyzing powers of the (d, τ) reactions on 16O, 28Si and 40Ca at 52 MeV have been observed and utilized to determine the spins of 1p hole states in 15N and 27Al and of 1d hole states in 39K. The results are pertinent to the empirical determination of the 1p and 1d spin-orbit splittings.

Strong exhaustion of 1gsol92 strength by deeply-bound proton-hole states in Pm isotopes☆

Abstract The 1 g 9 2 proton-hole strength distributions in Pm isotopes have been investigated by the 144, 148, 152 Sm (d,τ) reactions at 52 MeV. Other than for corresponding neutron-hole states most of the shell-model strength is exhausted by one gross structure peak.

The particle-hole spectra of 16O and 16N as observed in pick-up reactions from 17O

Abstract The reactions 17O(d, t) 16O and 17O(d, τ)16N have been investigated at Ed = 52 MeV. Energy spectra of tritons and τ-particles have been measured simultaneously up to excitation energies of 22 MeV in 16O and 10 MeV in 16N, respectively. Spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. From the comparison of the t- and τ-spectra analog (T = 1) states in 16O could be identified and the distribution of T = 0 and T = 1 spectroscopic strengths could be deduced. Nearly the total 1 p 1 2 and 1 p 3 2 hole strengths have been found and the 1 d 5 2 1 p 1 2 −1 and 1 d 5 2 1 p 3 2 −1 particle-hole multiplets could be located both for T = 0 and T = 1. The average residual interactions in both shell-model configurations turned out to be strikingly different.

Lifetime of nuclear hole states caused by phonon-hole coupling

Abstract Quasihole states in the 1d shells of 36,38,40 Ar and 40,42,44,48 Ca have been excited with the (d, 3 He) reaction at 52 MeV. A phonon-hole coupling model reproduces the measured spreading widths within typically 10 percent.

The (d, t) and (d, t) reactions on 18O and the 1p spin-orbit splitting☆

Abstract The reactions 18O(d, t)17O and 18O(d, τ)17N have been investigated at ifEd = 52 MeV. Energy spectra of tritons and τ particles have been measured up to excitation energies of 25 MeV in 17O and 12 MeV 17N, respectively, and spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. From a comparison of the t-and τ-spectra the distribution of T = 1 2 and 3 2 spectroscopic strengths in 17O could be deduced and analog relations between T = 3 2 states in 17N and 17O could be established. Nearly the total T = 3 2 strengths of the 1 p 1 2 and 1 p 3 2 shells and nearly the complete T = 1 2 strength of the 1 p 1 2 shell have been found, whereas only one third of the T = 1 2 strength of the 1 p 3 2 . Shell could be clearly identified. The observed centroid energies are understood from the different 1 d 5 2 1 p 1 2 − 1) and 1 d 5 2 1 p 3 2 −1 effective residual interactions. This supports a strong isospin dependence of the 1p spin-orbit splitting.

Comparative spectroscopy with the (d, τ) reaction on even Ar isotopes

Abstract The (d, τ) proton pick-up reactions on 36 Ar and 38 Ar have been studied at an incident energy of 52 MeV. Differential cross sections were measured and spectroscopic factors were extracted for transitions to 14 states of 35 Cl and 13 states of 37 Cl, respectively. Many new 5 2 + states and nearly the complete 1 d 5 2 strength have been observed in both nuclei. The width of the 1 d 5 2 spectral distribution is appreciably smaller for the semi-closed shell nucleus 38 Ar than for 36 Ar and 40 Ar. The results are compared with those from the 40 Ar(d, τ) reaction and proton stripping reactions on each of the three argon isotopes. Recent shell model calculations proved to be well suited to describe excitation energies as well as spectroscopic factors for the low-lying positiveparity states. Mirror relations were established for the nuclei 35 Ar and 35 Cl. In 37 Cl we succeeded in observing a weak component of a 1p proton hole state at a separation energy of only 18 MeV.

The mass and low-lying level structure of 17C

Abstract Spectra of 17 C ions from the 48 Ca( 18 O, 17 C) 49 Ti reaction at 102 MeV were recorded with a Q3D spectrograph. The lowest state observed, assumed to be the ground state of 17 C, has a mass excess of 21023±35 keV. An excited state of 17 C was also observed at an excitation energy of 292 ± 20 keV.

A model for the strength function of deeply bound hole states

A comparison of measured and calculated ld52 proton-hole strength distributions in a series of Cl, K and Sc nuclei demonstrates the large effect of phonon-hole coupling on the intermediate structures of the hole strength distribution. A model calculation allows us to study the influence of the high-lying hole strengths which cannot be observed in experiments on occupation probabilities, centroid energies and spreading widths.

Investigation of 1p-2h states in 39K with the 38Ar(3He, d)39K reaction

Abstract The 1p-2h aspect of 39K states was examined by means of the 38Ar(3He, d) reaction at E( 3 He ) = 24 MeV . Angular distributions for 17 states up to an excitation energy of 7 MeV have been measured and analysed with DWBA calculations to determine the transferred angular momentum and spectroscopic factors. Almost the complete transition strengths have been observed for 1f 7 2 and 2p 3 2 states in 39K with T = 1 2 . The isobaric analog state of the 39Ar g state with J π = 7 2 − was found at an excitation energy of 6547 ± 15 keV. The spectroscopic results represent a sensitive test of shell-model wave functions calculated previously by several authors.